The present invention relates to a parking brake apparatus in which, when an operating lever supported on a base member is operated, an operating force is transmitted to a brake unit through a brake cable to generate a braking force.
A conventional parking brake apparatus 100 is shown in FIG. 8. The parking brake apparatus 100 is disposed in the vicinity of a center console of an automobile, and a bracket 101 is mounted to a car body. A ratchet 102 is fixed to the bracket 101. A lever 104 is rockably pivoted to the bracket 101 by a pivotal pin 103, and a pawl 105 is rockably pivoted to the lever 104 through a pin 106. A nose of the pawl 105 can be engaged with a tooth part 102a of the ratchet 102.
A release rod 107 is connected to one end 105a of the pawl 105, and by pressing a release pushbutton 108 provided at one end of the release rod 107, the release rod 107 causes the pawl 105 to be released from the ratchet 102. When the pressing force is removed from the release pushbutton 108, a release spring 109 energizes the pawl 105 in a direction of being engaged with the tooth part 102a of the ratchet 102 through the release rod 107.
A cable guide 110 with a cable 113 wound thereon is provided on a side surface of the lever 104. One end of the cable 113 is fixed to the lever 104, and the other end is connected to a brake unit through the control cable. When a grip 112 is pulled, the cable 113 is drawn, so that the operating force is transmitted to the brake unit. At the same time, the energizing force of the release spring 109 causes the pawl 105 to make a repetitive motion while being guided by the tooth part 102a of the ratchet 102. With the pulling force of the grip 112, the pawl 105 is engaged with the tooth part 102a of the ratchet 102 through the action of the release spring 109. Accordingly, the grip 112 is locked to hold the braking force. When the release pushbutton 108 is pressed, the braking force is released.
In order to obtain a desired braking force in the parking brake apparatus 100, it is necessary to provide an appropriate lever ratio and output stroke (cable stroke). The lever ratio can be expressed as a ratio between a distance (L11) from the center of rotation of the lever 104 to a gripping part of the grip 112, and a distance (L12) from the center of rotation of the lever 104 to the cable 113. In order to provide the appropriate lever ratio and output stroke, the distance L11 needs to be 200 mm to 260 mm, and the output stroke needs to be approximately 30 mm.
However, when the distance L11 is 200 mm to 260 mm, it is necessary to install the center console in a limited space, or it is difficult for a passenger to walk through. Therefore, it is necessary to make the parking brake compact, thereby reducing the distance L11 without changing the lever ratio. That is, it is necessary to reduce the distance L12. When the distance L12 is reduced in a state that the cable 113 is wound on the cable guide 110 as mentioned above, the cable 113 is curved to a large extent. That is, every time the braking operation is performed, the cable 113 is heavily curved, thereby applying excess stress to the cable 113. Therefore, it is difficult to reduce the distance L12 and a size of the parking brake without changing the lever ratio.
In view of the problems described above, an object of the present invention is to provide a parking brake apparatus having a small size.